Ammonium Sulfide Oxide Removal on Semiconductor Surfaces
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Solution Overview
Problem
Native oxide films on semiconductor substrates pose difficulties in fabrication processes due to their thickness and high contact resistance, necessitating their removal before subsequent processing steps.
Innovation Solution
A method involving the use of ammonia and hydrogen sulfide to form ammonium sulfide, which etches away the native oxide layer, and optionally forming a sulfur layer for passivation or thickness reduction, allowing for controlled removal of the oxide layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If native oxide layer is present on semiconductor substrate, then substrate surface is naturally protected from further oxidation, but fabrication process difficulty increases and contact resistance becomes high
Solution Approach 1:
The patent removes the harmful native oxide layer from the semiconductor substrate surface using a selective etching process. The etch solution selectively removes the oxide layer while leaving the underlying semiconductor material intact, thereby extracting the problematic layer that causes fabrication difficulties and high contact resistance.
Solution Approach 2:
The patent changes the chemical parameters of the substrate surface by applying a controlled etching process that modifies the surface composition. By adjusting etch solution composition, temperature, and exposure time, the oxide layer is removed while controlling the etching rate to prevent damage to the semiconductor material.
2Reliability
If native oxide layer is present on semiconductor substrate, then substrate surface is naturally protected, but contact resistance in source and drain areas becomes high
Solution Approach 1:
The patent selectively removes the native oxide layer from source and drain areas where high contact resistance is problematic. By extracting the oxide layer in these specific regions, electrical contact is improved while maintaining substrate protection in other areas through controlled processing.
Solution Approach 2:
The patent applies selective oxide removal to specific regions (source and drain areas) rather than uniformly treating the entire substrate. This local approach reduces contact resistance where needed while preserving the protective function of oxide layers in other regions, creating different surface qualities in different locations.
3Stability of the object's composition
If native oxide layer is present on semiconductor substrate, then substrate surface is stable, but equivalent oxide thickness in channel areas increases
Solution Approach 1:
The patent removes the native oxide layer from channel areas to reduce the equivalent oxide thickness to precise target values. By extracting the unwanted oxide, the actual oxide thickness is controlled to match design specifications, improving manufacturing precision for subsequent processing steps.
Solution Approach 2:
The patent controls the oxide layer thickness parameter by applying controlled etching processes. By adjusting etch duration, temperature, and solution composition, the oxide thickness is precisely controlled to achieve target equivalent oxide thickness values while maintaining substrate stability through controlled processing conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively removes native oxide layers, reducing thickness and preventing re-formation, thereby improving semiconductor substrate quality for subsequent processing steps.
Implementation Method 1
reacting the ammonia with hydrogen sulfide to form ammonium sulfide, and then cleaning and removing the oxide on the semiconductor surface by the ammonium sulfide
Implementation Method 2
forming a layer of sulfur with the semiconductor surface, and then removing the layer of sulfur
Data Source
AI summary
Embodiments of the present disclosure relate generally to a method of passivating and/or removing oxides on a semiconductor surface by using ammonium sulfide, the ammonium sulfide is formed by reacting ammonia and hydrogen sulfide in a semiconductor processing chamber, therefore the ammonium sulfide can be used to clean and remove oxides on a semiconductor surface without the concern of ESH and storage, the ammonium sulfide can also be used to passivate a semiconductor surface by forming a layer of sulfur, and thus preventing the reformation of native oxides, the layer of sulfur can be optionally removed to reduce the thickness of the semiconductor material.